A far easier solution is to modify the SNAP / food stamp rules to limit purchases to healthy foods, such as what WIC permits today plus a few other healthy things like potatoes. Instead, she wants to tell those who feed the hungry to watch what they eat.
I have always thought it would be good to have an optional food stamp package that would only be for unprocessed food (vegetables, whole grains, seeds and nuts, and raw meat foul and fish), plus a modest amount for soap, toothpaste, razor blades and the like.